Political Psychology, Vol. xx, No. xx, 2011 doi: 10.1111/j.1467-9221.2010.00808.x An Evolutionary Account of Suicide Attacks: The Kamikaze Casepops_808 1..26 John Orbell University of Oregon Tomonori Morikawa Waseda University Explanations for suicide attacks abound. Yet the literature remains conceptually frag- mented, with different authors focusing on different attitudes, incentive structures, values, psychological processes, strategic imperatives, and cultural, historical, and personal cir- cumstances. Curiously, however, there have been few efforts to cast suicide bombing within the extensive evolutionary literature on human altruism—in which it clearly belongs. Neither have there been more than occasional efforts to mobilize the distinction between “proximate” and “ultimate” explanations, with most proposed explanations being proxi- mate. Here we draw on content analyses from materials written by Japanese Kamikaze pilots to propose an evolvable cognitive algorithm—by hypothesis, species typical—that (1) specifies environmental circumstances under which such “heroic” behavior is likely; (2) is consistent at the proximate level with the Japanese data; and (3) that is not inconsistent with many of the diverse proximate attitudes, values, and psychological mechanisms that dominate discussions of contemporary suicide campaigns. The evolutionary perspective is not an alternative to most of the proximate explanations offered in discussions of contem- porary cases but is, rather, a paradigm around which diverse proximate explanations can be organized. KEY WORDS: suicide attacks, evolution, kamikaze When trying to explain individuals’ participation in suicide attacks,1 diverse scholars have argued for diverse processes. Among these have been group 1 By which we understand attacks against members of some group, opposed to one’s own group, in the successful execution of which the attacker accepts that his or her life is inevitably forfeit. The frequently used term “suicide terrorism” unnecessarily confounds one proposed consequence of such an attack (“terror”) with the critical idea of the attacker’s accepting his or her own death. The more 1 0162-895X © 2011 International Society of Political Psychology Published by Wiley Periodicals, Inc., 350 Main Street, Malden, MA 02148, USA, 9600 Garsington Road, Oxford, OX4 2DQ, and PO Box 378 Carlton South, 3053 Victoria Australia 2 Orbell and Morikawa solidarity and an exclusive identification with the values of the group’s leader (Wintrobe, 2006); a willingness to trade personal welfare to support the welfare of future generations (Azam, 2005); the attempt at “significance restoration” after assaults on one’s personal significance (Kruglanski et al., 2009); social pressure and contagion within a context of violence and support for violence (Bloom, 2005; Bloom, 2009; Stern, 2004); the limited strategic opportunities with which popu- lations are confronted when threatened or occupied by overwhelming force (Pape, 2003; Pape, 2005); socialization of individuals into a culture or religion that peculiarly permits or requires a willingness to die in its defense (Post, 2007), and so on. The problem is not that any of these are necessarily wrong; all of them might be right, at least up to a point. All suicide attack campaigns happen within a complex mix of military, historical, strategic, cultural, and, sometimes, religious circumstances, any one of which might contribute to leaders’ decisions to initiate such a campaign. By the same token, every bomb-carrier’s decision to participate in such a campaign happens within a complex mix of personal, psychological, ideological, cultural, religious, social, and community considerations, any one of which might contribute importantly to that individual’s decision; intergenerational concern, “significance restoration,” social contagion, the absorption of particular religious and cultural values, and no doubt many other similar factors might, on occasion, all be involved, perhaps interacting in complex ways. Arguing about which of such proximate factors is most (or least) important in general is a futile exercise. The confusion, we believe, comes from scholars’ failure to discover a set of terms that organizes diverse levels of analysis, concepts, and causal processes in an integrative manner—that is to say, to settle on a paradigm that allows them to organize the processes on which they wish to focus so that a coherent picture emerges, one that specifies just where disagreements exist and what kinds of data might be necessary to resolve them. Such a paradigm would have to include species typical cognitive systems as well as environmental circumstances to which such systems might respond. Here we argue that such a paradigm is already available. Known variously as “Sociobiology,” “Evolutionary Psychology,” “Evolutionary Neuroscience,” and “Human Ethology,” it offers an evolutionary perspective on understanding the full range of human behaviors—including suicide attacks—and exploits the well- developed conceptual and analytic tools of Evolutionary Biology to that end. A goal of the present paper is to show how this paradigm can resolve the analytic confusion that presently surrounds social scientists’ efforts to come to grips with suicide attacks. general term “suicide heroism” would be appropriate if the behavior in question were not an attack per se—as when an individual willingly gives up his or her life to save others. An Evolutionary Account of Suicide Attacks 3 Curiously, this paradigm has been either ignored by scholars concerned with that topic (although not entirely; see Atran, 2003; Blackwell, 2008) or, too often, just acknowledged and then summarily dismissed, perhaps as too difficult for the task at hand (e.g., Gambetta, 2005, Foreward, p. ix; and “Can we make sense of suicide missions?” p. 271). This refusal to come to grips with evolutionary thinking—not unusual across the social sciences—might be studied with profit by philosophers of science (cf. Kuhn’s (1962) analysis of how paradigm shifts happen), but doing so is well beyond our present concern. Here we show that the broad terms of this approach can provide a framework for understanding suicide attacks, one that incorporates several levels of analysis in a coherent manner. We proceed inductively, starting from a content analysis of writings by pilots who died in the Japanese Kamikaze campaign in the later months of World War II. Of course, we do not claim that the historical and cultural circumstances of this particular campaign were the same as those within which more contemporary campaigns have happened; obviously, they were different in many ways. But it is possible that circumstances that are historically and culturally very different might invoke the same or similar emotional and behavioral responses from species- typical humans, in which case the problem is to recognize the commonalities to which those humans are responding and to understand why they are so responding. By looking in depth at the responses of the Kamikaze pilots to the circumstances in which they found themselves, we can propose species-typical cognitive systems capable of producing a willingness to engage in suicide attacks in circumstances that might seem very different in historical or cultural terms, but that do, never- theless, present humans with environmental stimuli that serve the same functional purpose of prompting a willingness to participate in suicide attacks. Induction does not, of course, prove anything (Popper, 1959), but it can provide a basis for hypotheses about the structure and functioning of human cognitive systems that are testable on different cases of the same behavioral phenomenon. In these terms, our present goal is to induct from what we can tell about the emotions and perceptions of the Kamikaze pilots contemplating their missions to species-typical cognitive systems that might, plausibly, underlie suicide attacks in general. At core is the proposition that cognitive systems are designed by natural selection to guide animals toward behaviors that increase their probability of surviving in particular environments and (critically) of passing their genes onto subsequent generations, given such environments. Necessarily, therefore, a cog- nitive system has the broad algorithmic structure IF [environment] THEN [behav- ior].2 Consistent with a broad consensus among evolutionary psychologists and cognitive scientists more generally, we accept that brains consist of a hugely 2 We emphasize the contingency involved in algorithms governing phenotypically plastic traits, a fact often overlooked by critics. Evolution designs systems to be context sensitive, implying one response to one circumstance and another to another. We also emphasize the probabilistic character of the term following [THEN]. While emotions supporting behavior are likely to be reflexive, the behavior itself 4 Orbell and Morikawa complex architecture of more and less specialized systems, each designed to address particular adaptive problems each with distinctive information and behav- ioral demands (Barrett & Kurzban, 2006; Gigerenzer, 1997; Sperber, 1994).3 Given the existence of such cognitive algorithms, two very different questions require an answer: 1) What selective pressures could have produced the hypothesized algorithm during the ancient past in which humans’ brains were being shaped by natural selection? 2) What design features would such selective pressures have incorporated, suf- ficient to serve the system’s adaptive function